Method and apparatus for connecting articles with a graded coating of glass



1951 v. PLAGGE METHOD AND APPARATUS FOR CONNECTING ARTICLES WITH A GRADED COATING OF GLASS Filed June- 29, 1945 7? Petr/Flinn INVENTOR KL. FL 17665.

Mm hwz ATTORNEY Patented Oct. 16, 1951 METHOD AND APPARATUS FOR CONNECT- ING ARTICLES WITH A GRADED COATING OF GLASS Vernon L. Plagge, East Orange, N. .L, assignor to Westinghouse Electric Corporation, East Pittsburgh, Pa., a corporation of Pennsylvania Application June 29, 1945, Serial No. 602,259

6 Claims. (Cl. 49-81) This invention relates to applying coatings of glass to metal and glass articles, as for the purpose of uniting such articles, as well as uniting metal or glass articles to other metal or glass articles of different compositions.

The principal object of my invention, generally considered, is to apply coatings of glass of the desired character to metal, as well as glass, surfaces preliminary to uniting glass to metal and/or glass or metal to glass and/or metal.

Another object of my invention is to apply coatings of glass to metal or glass surfaces, in which the coating glass is first prepared by crushing, grinding, forming into a smoke, charging said smoke to a potential different from that of the article to be coated, whereby the glass particles in said smoke stick to said article, and fusing the coating of glass on said article.

A still further object of my invention is to prepare a graded seal by bringing the outlets from two generators of a glass smoke, or gaseous suspension of finely-divided glass, to a single nozzle, said generators respectively containing glass of different compositions. and the outlets therefrom being independently controllable by valves, so that the composition of the glass smoke delivered from the common nozzle may vary from that of one generator gradually to that of the other, thereby making it possible to apply coatings of desired composition, as well as changing the character of said coatings at will during coating operations.

Other objects and advantages of the invention will become apparent as the description proceeds.

Referring to the drawing:

Fig. 1 is an elevational view, partly in vertical section, of apparatus for practicing my invenview of a discharge device which may be made using the generator of Fig. 5.

Fig. 7 is a view corresponding to Fig. 6, but showing a modification.

Referring to the drawing in detail, like parts being designated by like reference characters, and first considering the embodiment of my invention illustrated in Figs. 1, 2 and 3, there is shown a table or support II to which is secured a pedestal [2, through which extends a shaft l3 journalled therein, having a head It at its upper end provided with an upwardly opening pocket I5 which receives a block I6 having a plurality of upwardly opening sockets ll for receiving metal wires l8.

The lower end of the shaft 13 carries a pulley I9 engaged by belt 2! from a suitable drive motor, not shown in order to cause rotation of the head it and wires 18 carried thereby. The pedestal i2 is desirably grounded, as indicated at 22, although as an alternative it may be insulated from the table II and maintained at a desired potential.

The reference character 23 designates a "smoke generator, which may correspond structurally with that designated 36 in the McGowan application, Ser. No. 445,246, filed May 30, 1942,

Fig. 5 is a fragmentary view of apparatus for generating glass "smoke" of a controlled character.

and now abandoned. However, in this instance,

. the smoke" is to be made from powdered glass,

of less than IOO-mesh, and preferably less than ZOO-mesh.

The powdered glass is then deposited in the housing 24, of the smoke generator 23, which is suspended from the table or support II as by means of brackets 25. It may carry a drive motor connected to a shaft 26 journalled in the housing cover 30, or said shaft may carry a pulley 21 driven in any suitable manner, as by means of the belt 2|. To the lower end of the shaft 26 are secured stirring wires or the like 28. at least partially submerged in the finely-divided glass 29 in the housing 24, whereby operation of the shaft elfects a continuous stirring of the powdered glass.

The lower portion of the housing 24 is de- Fig. 6 is a fragmentary longitudinal sectional at sirably frusto-conical in shape and terminates in a spout or cylindrical projection 3|, receiving the end of an air nozzle 32. connected thereto in any desired manner, as in the McGowan application referred to. The air from the nozzle is controlled by suitable means such as valve 33. Said nozzlefits in a pipe 34, the lower portion of which is relatively large and provided with apertures 35, while the upper portion is reduced in section to a nozzle tip, as indicated at 38.

By virtue of this construction, compressed air may be admitted to the housing through air hose 31, to blow the agitated glass particles 29 which feed through the apertures 35, through the upper end of the reduced section 36, to impinge against the hub 88 of the stirring wires 28, thereby generating an air suspension of said finely divided glass, making a smoke, and delivering it to a nozzle 39, preferably formed of insulating material and carrying an electrode 4i adapted to be charged to a relatively-high preferably positive potential.

The method of using the apparatus previously described may be as follows. A plurality of wires 18 are placed in corresponding sockets ll of the supporting block I8, where they are rotated upon operation of a drive motor, or other operating means. In the present embodiment, the wires it are adapted for leads for electrical device, and shown as formed in three parts, the center parts being of Kovar or other material which seals well through glass. Instead of Kovar," I may use tungsten, molybdenum, dumet, as disclosed in the Fink Patent No. 1,498,908, or other selected lead-wire material. The end portions of the leads may be of copper, or other selected material, connected to the center portions by butt welds.

The intermediate portions of the leads are oxidized while being rotated, as by subjecting them to the flame of a gas burner 43 until the oxide thereon is just enough to roughen the wire surface, while being capable of absorption by the glass coating to be applied thereto. In other words, the surface to be coated with glass is oxidized or otherwise roughened, that is, by acid or sand-blasting, as more specifically disclosed in the Pask et al. application, Ser. No. 591,998, filed May 4, 1945, now Patent No. 2,560,593, and owned by the assignee of the present application.

After the leads are sufllciently roughened or oxidized, as illustrated in Fig. 1, the burner 43 is f removed or shut off, and the valve 33 adjusted to discharge the selected smoke 44 in a stream on the intermediate portions 42 of the leads l8, while they are still rotated, the axis of such rotation being substantially perpendicular to the line of direction of said stream, as shown most clearly in Fig. 2. During this operation, the electrode 4| is charged to a high preferably positive potential, such as about 9000 volts, thereby giving the glass particles which flow thereover a high electrostatic charge and causing them, for that reason, to be attracted to the oppositely charged, relatively negative, or grounded leads ll, to build up a coating of powdered material to the desired thickness.

when this has been accomplished, the valve 33 is shut off and the burner 4! brought into position, as illustrated in Fig. 3, to fuse the coating of powdered glass to firmly adherent films or beads 45 on the leads ll, or the intermediate portions thereof, as shown most clearly in Fig. 3, as by heating to the correct temperature for a suitable time interval. Heating for about four minutes at about 1000 C. has been successfully used. These beaded leads may now be used in vacuum or other electrical devices to form parts of mounts 46, for example, as shown in Fig. 4, where a pair of beaded leads I! are shown incorporated in the press 41 of the mount 46, forming part of a discharge device only one end of which is illustrated. The glass coating on the leads, of any thickness desired, from one to ten mils, for example, either forms a graded seal between the leads and the glass of the press, if of material having expansion characteristics intermediate those of the leads and press glass, and/or insures against leakage along said leads.

The foregoing description is applicable to coating conductive or metal articles, such as wires, where it is possible to ground the article being coated or charge it to a potential different from that of the glass particles forming the coating. When a glass or non-conductive article is being coated, the same may be effectively grounded, or charged to a potential different from that of the glass particles by heating to a point where it becomes conducting. As an alternative, a plate or film of conductive material may be applied back of the surface to be coated, and grounded or charged to a potential different from that of the glass particles, the conductive plate or film thereby causing the latter to adhere to the non-conductive surface in a similar manner.

Referring now to the embodiment of my invention illustrated in Fig. 5, there is shown a pair of smoke generators 23 and 23'', corresponding with the generator 23 of the preceding embodiment, and supplied with compressed air from air hose 31', which branches and through separate valves 33- and 31 connects with the generators 23 and 23 respectively. The outlet pipes 48 and BI from said generators are respectively controlled by valves 52 and ll, which may be independently operated, or their operating handles 64 and II connected by a rod ll, so that as one valve, II, for example, initially open, is being closed while valve 53, initially closed, is being opened.

By virtue of this arrangement, it is possible to put powdered glass, having a certain expansion characteristic, in one of the generators, and powdered glass of a different expansion characteristic, in the other generator. and deposit glass from the smoke generated, which may be directed by the pipes 49 and Ii to common discharge pipe '51 which goes from there to a nozzle like that designated 38 in the preceding embodiment, on leads or any other surface which it is desired to coat, as in the preceding embodiment.

During the process of coating, the composition of the smoke may be changed, by gradually closing one valve 52 and opening the other valve ll. so that the first coating deposited may, for example, have an expansion characteristic corresponding with that of the surface on which deposited. the expansion characteristic of said coating being gradually changed as it is built up, until the last layer of powdered glass has a diflerent expansion characteristic which may correspond with that of the glass or other material to which the coated wire, or other object, is to be united, thereby creating a uniformly-varying graded seal between metal and glass, metal and metal, or glass and glass. as the case may be.

As an alternative, as when the expansion characteristics of the parts to be united are not greatly different, one generator may contain glass having an expansion characteristic making it properly scalable to one of the parts to be united. but of expansivityintermediatethosedthetwopattl.

andtheothermaycontainpowderedglass of theexpansivityintermediatetha'toftheglassof' the other generator and that of the other but satisfactorily scalable to-the latter. I thefirstpartmaybeprovidedwithacoatingof glassfrom one generator,andthesecondpart further alternative, oneof the parts may have a coafingofglasfromonegeneratonsaidglass.

beingthenfusedthereonand-thenacoaflngof glasskappliedfromtheothergeneratorand flmedthereomwhereuponitissealedtoanother part,thelayersofglasshavingexpansloncharacterlsticsmakingaproperlygradedsealbctween thetwoparts.

Fig. 6 illustratesaproductoftheapparatus andmethoddescribulinconnectlonwithl'igj.

The reference character I! designates an envelope for a discharge device, and thereference charafierisdesignatesasupportorleadforan electrodeil thereof. t'lheleadlliscoatedwith glassl2.asfrom generatorll whichhascharacteristicsmakingitsealproperlytothematerial thereof aml. if different. desirably approaching the expansion characteristics of the material forming the envelope it. After this coating of powderedglasshasbeenfusedonthewire,as described in connection with the first embodiment. a'second coating ii is applied thereover, this being from generator I! which contains glass properly scalable to that from generator 23*, and having expansion characteristics makingitalsoproperlysealabletothemateriaiionningtheenvelope l,asbybeing.ifditferentin expansivity. intermediate that of the material of the firstcoating and that of the envelope. Afterthissecondcoatinghubeenfusedonthe firstcoatinmthebeadedleadilisthensealedto theenvelope-formingagradedsealasillustrated in .6.

lfiflllustratesaconstructionsimilartol igj, exceptthattheenvelopewisconnectedtothe leadil carryingtheeiectrodeilfibyheadingfl formed by starting the application of a coating from smoke from the generator 23 containing glasssufiicientlymatchingtheexpansioncharacteristicsoftheleadihandgraduailyvarying From the foregoing, it will be seen that I have to not onh provided for conveniently applying a beadorcoatingofglasstoawire,oranyother desired article, but have made it possible to convary the expansion characteristics of wherebyawireoroflierobiectuuranimn. ItisdesignatedasER.0anaryand 6 may be satisfactorily united to another wire. or other object such as a glass envelope, by a con- 'veniently-formed graded seal.

In thepastthis hasbeen done by a succession of 0 layers of glass, which form a series of expansion steps. Many times the glasses are not available for the intermediate steps, and in other cases the cost of performing these operations is exorbitant. In accordance with my method, by using two 10 smoke generators. if containing powdered glasses whose expansion characteristics are at the ends of expansion range desired to be bridged, I am enabled to conveniently unite two objects. whether they be both metal, both glass, or one ii metal and one glass, by a series of glasses in either definite steps or through imperceptible The glass employed for coating depends on the expansion characteristics of the article to be coated. Any of the common glasses used for heading, in connection with making glass to'metal seals, may be employed. When the wire or lead is made of tungsten, for example, I may use any one of Corning glasses Nos. 772, 3320. and 775. 28 When made of Kovar" as defined in the Lempert et al. Patent No. 2,279,831, for example, or molybdenum, for example, I may use either of 7 Coming glasses Nos.704 and 7052. When it is desired to apply glass to glass or other non-con- 30 ductive surface; the glass from which the powder is made may be made of the same kind of glass as that of the article to be coated, or one modified by the addition of another glass, to make a graded seal with respect to another article of glass. or

a metal article towhich the glass is to'be connected.

Corning glass No. 704 is a potash-borosilicate glass containing a small percentage of alumina. It is sold under the trade mark Pyrex," labora- 40 tory No. G-705-BA, for radio special sealing. It

has a softening point at 702+7 0., an annealing point at 484 0.. a strain point at 450 0., a coefiicient of expansion of 47.5:1.5x10" between 0 and 300 0., a working point at approximately 1080" 0., and a density of 2.24. The

logic of its resistivity at 350 0. is 7.95. Its power factor is .0018 (expressed as a decimal-not as percent), its dielectric constant 4.8, and its loss factor .0086 (expressed as a decimal-not as percent) Corning glass No. 772 is a soda-lead-borosilicate glass. It is designated H. R. clear Nonex," laboratory No. G-702-P. It has a softening point at 755- -5 0., an annealing point at 518 0., a

5 strain point at 484 0., a coeflicient of expansion of 361:1)(10 between 0 and 300 0., a working point at approximately 1110 0., and a density of 2.35. The logic of its resistivity at-350 C. is 7.2, its power factor is .0027; (expressed as a m decimal-not as percent), its dielectric constant 4.7, and its loss factor .0128 (expressed as a decimal-not as percent).

Corning glass No. 775 is a soda aluminum borosciliciate I glass, differing from No. 774 by bea ing lower in silica and higher in boric oxide. It

is designated a clear sealing glass, laboratory No. G-705-R. It has a softening point at 704 0., an annealing point at 476 0., a strain point at 431 0.. a coeflicient of expansion of between 0 and 300 0., and a density of 2.19.

Coming glass No. 3320 is a soda-aluminumborosilicate glass with a small percentage of sold under the trade-mark Pyrex, laboratory No. (3-371 BN. It has a softening point at 780 C., an annealing point at 535 C., a strain point at 497 C., a coefficient of expansion of 40:l 10-" between and 300 C., and a density of 2.29.

Corning glass No. 7052 is a potash-bariumborosilicate glass sold under the trade-mark Pyrex, laboratory No. G-705-FN, for sealing purposes. It has a softening point at 708i5 C., an annealing point at 480 C., a strain point at C., a coefficient of expansion of between 0 and 300 C., a working point at approximately 1115 C., and a density of 2.29. The logic of its resistivity at 350 C. is 7.40. Its power factor is .0026, (expressed as a decimal-not as percent), its dielectric constant 5.1, and its loss factor .0133, (expressed as a decimal-not as percent).

By employing my invention, it is possible to eliminate the use of all beading glass tubing and the operation of cutting such to the required length. The glass powder for the smoke is cheaply and conveniently provided by using scrap glass from cullet sealing, flare making, and other glass operations. Uniformity of quality can be readily specified and closely controlled, eliminating the personal element. The process, because of its flexibility lends itself readily to high speed production. Oxidizable articles, such as metal leads and other metal parts, may be coated with glass, in accordance with my invention, in a controlled or non-oxidizing atmosphere, thereby preventing undesired oxidation, and afterwards the glass film or coating thereon protects the metal from oxidation during subsequent heating operations.

Although preferred embodiments have been disclosed, it will be understood that modifications may be made within the spirit and scope of the invention.

I claim:

1. Apparatus for coating articles comprising means for generating a gaseous suspension of finely-divided glass powder having certain expansion characteristics, similar means for generating a gaseous suspension of finely-divided glass powder having different expansion characteristics, means for causing said gaseous suspensions to flow toward, and be mixed in a common conduit,

and means for varying the proportions of the suspensions to change the mixture at will, and a nozzle at the end of said common conduit, so that the glass suspension emitted from said nozzle has characteristics, selectively controllable as desired.

2. The method of applying a firmly adherent graded coating of glass to a surface of an article, capable of withstanding fusion of glass thereon. adapting it to be united to an object having a coefficient of expansion different from that of said 8 that of said initial mixture to that of said final mixture, and heating to fuse the adhering particles as a uniformly-varying graded coating on I said surface.

3. The method of applying a firmly adherent graded coating of glass to a metal wire, capable of withstanding fusion of glass thereon, adapting it to be united to a glass envelope having a coefficient of expansion different from that of said wire, comprising blowing onto said wire a gaseous suspension of a composition consisting of two lasses as finely-divided particles, said glasses having different coeflicients of expansion, the initial mixture of the glasses having a coefficient of expansion corresponding to that of the wire and the final mixture having a coefilcient of expansion corresponding to that of the envelope, charging the glass particles to a high potential relative to the wire being coated as they move toward said wire, thereby causing the glass particles to adhere to said wire, and during the blowing operation gradually changing the proportions of the particles of the two glasses from that of said initial mixture to that of said final mixture, and heating to fuse the adhering particles as a uniformly-varying graded coating on said wire.

4. The method of applying a firmly adherent graded coating of glass to a front surface of a non-conductive article. capable of withstanding fusion of glass thereon, adapting it to be united to an object having a coefficient of expansion different from that of said article, comprising placing a conductive plate back of said article, blowing onto said surface a gaseous suspension of a composition consisting of two glasses as finely-divided particles, said glasses having different ccefiicients of expansion, the initial mixture of the glasses having a coeificient of expansion corresponding to that of the article and the final mixture having a coeiilclent of expansion corresponding to that of the object, charging the glass particles to a high potential relative to the plate as they move toward said article, thereby causing the glass particles to adhere to said sur- 0 face, and during the blowing operation gradually that of said final mixture, and heating to fuse article. comprising blowing onto said surface a gaseous suspension of a composition consisting of two glasses as finely-divided particles, said glasses having different coefilcients of expansion, the initial mixture of the glasses having a coefficient of expansion corresponding to that of the article and the final mixture having a coeflicient of expansion corresponding to that of the object, charging the glass particles to a high potential relative to the article being coated as they move toward said article, thereby causing the glass particles to adhere to said surface, and during the blowing operation gradually changing the proportions of the particles of the two glasses from the adhering particles as a uniformly-varying graded coating on said surface.

5. The method of connecting first and second articles, both of which are capable of withstanding fusion of glass thereon and which have different coeflicients of expansion, comprising blowing onto the surface of the first article a gaseous suspension of a composition consisting of two glasses as finely-divided particles, said glasses having different coefficients of expansion, the initial mixture of the glasses having a coefilcient of expansion corresponding to that of the first article and the final mixture having a coefficient of expansion corresponding to that of the second article, charging the glass particles to a high potential relative to the article being coated as they move toward said article, thereby causing the glass particles to adhere to said surface. and during the blowing operation gradually changing the proportions of the particles of the two lasses from that of said initial mixture to that of said final mixture, heating to fuse the adhering particles as a uniformly-varying coating on said first article, and by fusion uniting the coated portion of said first article to said second article.

6. The method of connecting a metal wire to a glass envelope, both of which are capable of withstanding fusion of glass thereon and which have different coefflcients of expansion, comprising blowing onto the surface of the wire a gaseous suspension of a composition consisting of two glasses as finely-divided particles, said glasses 5 having difierent coefficients of expansion, the initial mixture 01 the glasses having a coefiicient of expansion corresponding to that of the wire and the final mixture having a coefiicient of expansion corresponding to that of the envelope, charging the glass particles to a high potential relative to the wire being coated as they move toward said wire, thereby causing the glass particles to adhere to said wire, and during the. blowins operation gradually changing the proportions of the particles of the two glasses from that of said initial mixture to that of said final mixture, heating to fuse the adhering particles asa unii'ormly-varying coating on said wire, and by iusion uniting the coated portion of said wire 20 to said envelope.

VERNON L. PLAGGE.

10 REFERENCES CITED The following references are of record in the file of this'patent:

UNITED STATES PATENTS Number Name Date Re. 22,419 Smyser' Jan. 11, 1944 267,318 Beach Nov. 14, 1882 1,173,688 Thomson Feb. 29, 1916 1,566,911 I Nelson Dec. 22, 1925 1,698,845 Gustin Jan. 15, 1929 1,774,694 Bateman Sept. 2, 1930 1,863,782 Young June 21, 1932 2,128,327 Russell et a1. Aug. 30, 1938 2,220,742 Thorson Nov. 5,- 1940 2,239,551 Dalton Apr. 22, 1941 2,271,125 June Jan. 27, 1942 2,334,648 Ransburg Nov. 16, 1943 2,424,353 Essig July 22, 1947 Kearsley Mar. 30, 1948 

5. THE METHOD OF CONNECTING FIRST AND SECOND ARTICLES, BOTH OF WHICH ARE CAPABLE OF WITHSTANDING FUSION OF GLASS THEREON AND WHICH HAVE DIFFERENT COEFFICIENTS OF EXPANSION, COMPRISING BLOWING ONTO THE SURFACE OF THE FIRST ARTICLE A GASEOUS SUSPENSION OF A COMPOSITION CONSISTING OF TWO GLASSES AS FINELY-DIVIDED PARTICLES, SAID GLASSES HAVING DIFFERENT COEFFICIENTS OF EXPANSION, THE INITIAL MIXTURE OF THE GLASSES HAVING A COEFFICIENT OF EXPANSION CORRESPONDING TO THAT OF THE FIRST ARTICLE AND THE FINAL MIXTURE HAVING A COEFFICIENT OF EXPANSION CORRESPONDING TO THAT OF THE SECOND ARTICLE, CHARGING THE GLASS PARTICLES TO A HIGH POTENTIAL RELATIVE TO THE ARTICLE BEING COATED AS 